One sleeve has a pin that fits into the corresponding hole; the other can be used for color marking. Make sure to position the stop towards the print bed.
I used a DC power jack socket like: https://www.amazon.de/Kontaktschalter-Hohlstecker-Niedervolt-Einbaubuchse-Pigtail-Silver/dp/B0975TSZRV
The author marked this model as their own original creation.